Models are frequently formed from polymeric material, sometimes being a foam material having a dense skin, and although not limited to such covering material this invention is applicable thereto. However previously formed models have not been suitably arranged to provide articulation between the joints in a way which will satisfactorily simulate human or animal movement, and in some cases very crude hinge means have existed, for example between the torso and arms or legs of a doll. In the case of a "shop model" used for display purposes for garments, it is extremely desirable that the positions of the limbs can be arranged in the best manner for such purposes, and this involves at least some articulation of the limbs with respect to one another and with respect to the torso in a way in which human or animal attitudes can be simulated.
Another problem which can be encountered in the construction of a model is that the foam plastics material which encases the torso and limbs will tend to flow between the moving parts in such a way that articulation is at least partly inhibited, and another object of the invention is to provide an articulation hinge which will inhibit such flow such that the model skeleton can be encased in moulded polymeric material and still allow articulation of the joints. In an embodiment of the invention, a model skeleton comprises a plurality of interconnected members, hinge joints joining some at least of adjacent said members for relative articulation between those members and a skeletal torso such as to effect partial simulation of animal movements, each said hinge joint comprising a pair of projections projecting from one member engaging walls of an adjacent member for relative rotation, a barb on the projection retaining that engagement, and sealing surfaces surrounding the projection and effecting a friction imparting seal between those members.
In some embodiments the sealing surfaces comprise a resilient flange or skirt of one member which is deflected by the other member upon engagement, and in other instances comprises an O-ring, formed of rubber or other polymeric material which has appropriate snubbing characteristics.
By selecting O-ring size, freedom of relative rotary movement is effectively snubbed, being partly inhibited by the O-ring. Thus it is possible to so arrange the articulating members that they will remain in a position in which they are placed. Similar results can be achieved by suitable interference fits between mating parts.
As said above, one of the problems encountered heretofore has been the tendency for the fluent polymeric material to flow between the articulating surfaces and inhibit articulation, and in another embodiment of this invention there is such an interengagement between the surfaces of the elements of each articulated joint that the space in which an annular flange or skirt, or the O-ring, is contained is protected against influx of fluent foaming polymeric material when the body is moulded over the skeleton of the model. If the elements are formed from a slightly resilient material such as nylon 6, glass-filled polycarbonate or the like, an interference can exist between the hinged elements and the O-ring (if selected) can be housed in an annular space which is protected by that interference against any such influx. Furthermore, the assembly can be quickly and easily effected by a "snap in" movement.